1. Field of the Invention
The present invention relates to a method of producing a pressure container filled with a propellant and including forming an outer container having a filling material chamber for receiving a filling material, forming an inner bag having a propellant chamber for storing the propellant, inserting the inner bag into the outer container, and closing the outer container, and closing the outer container with a cover provided with an inlet/outer valve, and a pressure container produced by the above-discussed method.
2. Description of the Prior Art
Pressure containers of the type discussed above are used, e.g., in gas-operated setting tool, with fuel being stored in the containers.
A liquified gas, which is stored in such pressure containers is used, e.g., for driving combustion-engined bolt setting tools. In the bolt setting tool, the pressure containers or pressure capsules are arranged with a possibility of their replacement and are provided, e.g., with a metering head that is secured on a pressure capsule, e.g., with snap connection means. In an operational condition of the bolt setting tool, the system pressure container/capsule and the metering head are located in a receptacle formed in the setting tool. In many applications, the liquified gas needs to be fed in its liquified phase in each possible orientation of the pressure container or capsule to insure a correct metering of the liquified gas/fuel.
Generally known are one-chamber and two-chamber pressure containers. Thus, German laid-open patent application DE-OS 362 66 b1 discloses a one-chamber pressure container with propellant and a filling material being located in the chamber of the container and with the propellant being partially dissolved in the filling material.
With one-chamber pressure containers, a problem consists in that discharging of the liquified gas in its liquid phase at each orientation of the pressure container is not possible because the gaseous propellant phase and the dischargeable liquid filling material are always oriented in the chamber in accordance with the gravity force. The discharge of the liquid phase of the liquified gas is possible only with a transverse pressure container with an upwardly extending valve (with a riser on the discharge valve) or in a position with a downwardly oriented valve (a valve without a riser).
With a two-chamber pressure container, discharge of the liquid filling material is possible at each orientation of a pressure container.
A two-chamber pressure container is disclosed in U.S. Pat. No. 5,069,590. In this container, an inner, thin-wall metallic container, in particular, an aluminum container, is arranged in an outer, thick-wall container, e.g., likewise formed of aluminum. At the opening of the pressure container, the two containers are folded or rolled over one another. The opening is closed with a cover provided with a valve. The filling material fills the inner container, and the propellant is located in the outer container.
The drawback of the pressure container of U.S. Pat. No. 5,069,590 consists in that the inner container with a relatively large amount of the filling material is subjected to strong mechanical stresses when acceleration forces act on the container. Further, some of the propellant can leak from the outer container through the rolled crimp. The ratio of the propellant to the filling material in fuel pressure containers for setting tools amounts approximately to 5/40 (e.g., 5 g/40 g). In particular, with a long storage and with a loss of the propellant 3-4 g per year, the pressure container can become unusable. Furthermore, two-chambers pressure containers are more expensive in production than one-chamber pressure containers.
Therefore, its is advantageous when the propellant is located in the inner container because in this case, the loss of the filling material or fuel influences the operating ability of the pressure container much less than the loss of the propellant.
U.S. Pat. No. 2,815,152, from which the present invention proceeds, discloses a method of producing a pressure container and a container produced by the method where the propellant is located in an inner container, which is formed as a freely movable, flexible bag, and the filling material is located in the outer container. The inner container is closed from all sides and contains the propellant in both liquid and gaseous phases.
According to the method disclosed in U.S. Pat. No. 2,815,152, after the inner bag is formed, the propellant is introduced into the bag under pressure sufficient to retain the propellant in the liquid phase. Then, the bag is closed. Thereafter, the bag and a predetermined amount of the filling material are brought together into the outer container which is closed under temperature and pressure conditions sufficient to retain the filling material in its liquid phase.
The method of U.S. Pat. No. 2,815,152 is rather expensive because during the entire manufacturing stage, a high pressure needs to be applied to the components of the pressure container to prevent evaporation of the propellant.
Accordingly, an object of the present invention is a method of producing a pressure container filled with a propellant of a type discussed above, but without the drawbacks of the prior art.